override ttl=0

[Mark Andrews]

> Hi everybody,
> I'm getting troubles with a DNS-ALG machine that send ttl=0 for every
> question I send to it.
> I browsed archive but did not find any solution to my problem.
> I just need to override ttl for A record when the ttl=0.
> Here a patch for bind 9.3.3rc2 (redhat 5.0).
> I know, that TTL should not be overrided, but in some case this
> functionality can be helpfull.

	Tell us the manufacture of the DNS-ALG so we can all avoid
	such a broken product.  The DNS requires caching to work.
	Any DNS-ALG that don't pass on the TTL is broken.
 
> The status of this patch is 'works for me'.
> 
> Please let me know if there is another implementation
> 
> Regard
> Hervé Guehl
> 
> Note : dont blame me if i'm not using the right list, just say me where I
> should write
> 
> 
> 
> diff -urN bind-9.3.3rc2.ori/bin/named/server.c bind-9.3.3rc2
> /bin/named/server.c
> --- bind-9.3.3rc2.ori/bin/named/server.c        2006-05-24 06:30:
> 24.000000000 +0200
> +++ bind-9.3.3rc2/bin/named/server.c    2007-12-18 22:01:47.000000000 +0100
> @@ -1245,6 +1245,11 @@
>         result = ns_config_get(maps, "max-cache-ttl", &obj);
>         INSIST(result == ISC_R_SUCCESS);
>         view->maxcachettl = cfg_obj_asuint32(obj);
> +
> +       obj = NULL;
> +       result = ns_config_get(maps, "override-zero-cache-ttl", &obj);
> +       INSIST(result == ISC_R_SUCCESS);
> +       view->overridezerocachettl = cfg_obj_asuint32(obj);
> 
>         obj = NULL;
>         result = ns_config_get(maps, "max-ncache-ttl", &obj);
> diff -urN bind-9.3.3rc2.ori/lib/dns/include/dns/view.h bind-9.3.3rc2
> /lib/dns/include/dns/view.h
> --- bind-9.3.3rc2.ori/lib/dns/include/dns/view.h        2004-03-10 03:55:
> 58.000000000 +0100
> +++ bind-9.3.3rc2/lib/dns/include/dns/view.h    2007-12-18 22:02:
> 01.000000000 +0100
> @@ -116,6 +116,7 @@
>         isc_boolean_t                   requestixfr;
>         isc_boolean_t                   provideixfr;
>         dns_ttl_t                       maxcachettl;
> +       dns_ttl_t                       overridezerocachettl;
>         dns_ttl_t                       maxncachettl;
>         in_port_t                       dstport;
>         dns_aclenv_t                    aclenv;
> diff -urN bind-9.3.3rc2.ori/lib/dns/resolver.c bind-9.3.3rc2
> /lib/dns/resolver.c
> --- bind-9.3.3rc2.ori/lib/dns/resolver.c        2006-08-31 05:57:
> 11.000000000 +0200
> +++ bind-9.3.3rc2/lib/dns/resolver.c    2007-12-18 22:02:56.000000000 +0100
> @@ -3537,6 +3537,11 @@
>                         rdataset->ttl = res->view->maxcachettl;
> 
>                 /*
> +                 * HGU configure minimum ttl if ttl=0 for A record
> +               */
> +               if  ( (rdataset->ttl == 0) && (rdataset->type ==
> dns_rdatatype_a) )
> +                        rdataset->ttl = res->view->overridezerocachettl;
> +               /*
>                  * If this rrset is in a secure domain, do DNSSEC validation
>                  * for it, unless it is glue.
>                  */
> diff -urN bind-9.3.3rc2.ori/lib/isccfg/namedconf.c bind-9.3.3rc2
> /lib/isccfg/namedconf.c
> --- bind-9.3.3rc2.ori/lib/isccfg/namedconf.c    2006-03-02 01:37:
> 20.000000000 +0100
> +++ bind-9.3.3rc2/lib/isccfg/namedconf.c        2007-12-19 15:11:
> 49.000000000 +0100
> @@ -715,6 +715,7 @@
>         { "lame-ttl", &cfg_type_uint32, 0 },
>         { "max-ncache-ttl", &cfg_type_uint32, 0 },
>         { "max-cache-ttl", &cfg_type_uint32, 0 },
> +       { "override-zero-cache-ttl", &cfg_type_uint32, 0 },
>         { "transfer-format", &cfg_type_transferformat, 0 },
>         { "max-cache-size", &cfg_type_sizenodefault, 0 },
>         { "check-names", &cfg_type_checknames, CFG_CLAUSEFLAG_MULTI },
> 
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org